Process of purifying brine.



Patented March 22, 1904.

rnnr Q WILLIAM TRANTOM, OF NEW BRIGHTON, ENGLAND.

PROCESS OF PURIFYING BRINE.

SPECIFICATION forming part of Letters Patent No. 755,415, dated March22, 1904.

Application file. November 25, 1902.

[0 mil whom it pea/y concern.

Be it known that I, WILLIAM TRANTOM, commission merchant, a subject ofthe King of Great Britain, residing in New Brighton, in the county ofChester, England, (whose full postal address is 10 Field road, NewBrighton. aforesaid,) have invented certain new and useful Improvementsin the Purification of Brine and other Alkaline Chlorid Solutions, (forwhich application has been made in Great Britain, ProvisionalApplication No. 23,6 l2, dated October 29, 1902,) of which the followingis a specification.

This invention has for its primary object the complete purification ofordinary brine, especially such brine as is used in electrolytic worksfor producing soda and chlorin. In these it is very desirable that thebrine should be chemically pure. It is also useful for obtaining saltfrom brine for domestic and other purposes Where great purity of productis desirable.

Further, the invention is useful for purifying chlorid of potassium orother alkaline chlorid salts or saline solutions from sulfate of limeand sulfate of magnesia or from the chloridsof calcium and magnesium.

The principal impurities in ordinary natural brine consist of thesulfates and the chlorids of calcium and magnesium.

I will describe my process first as it applies to a brine orchlorid-of-potassium solution containing all these salts. In order toprecipitate the chlorids of calcium and magnesia, I add sulfate of sodato the brine or sulfate of potassium to the chlorid-of-potash solution.The chemical reactions in the case of brine when ordinary monosulfate ofsoda is used are as follows:

CaCl2+Na2SOi CaSOi+ QNaOl MgCla+NtzSOr I MgSOi+ QNEtCl,

the result being that the brine treated now resembles a natural brine inwhich all the lime and magnesia are in the form of sulfate of lime andsulfate of magnesia. .If chlorid-ofpotassium solution had been treatedwith sulfate of potassium, a similar result would have ensued. If in thebrine there is a large amount Serial No. 132,784. (No specimens) ofsulfate of magnesia, it may be desirable to save this magnesia. In suchcase I replace the magnesia compound with sulfuric acid by limeaccording. to the equation MgSOH- Ca(OH)2 I CaSQ-l-MgOOI-Ih.

The hydrate of magnesia being insoluble in the brine can now beseparated by filtration or otherwise. The brine now containing only asimpurities sulfate of lime, or if it has been not worth while to savethe sulfate of magnesia also, I add to it freshly-precipitated carbonateof barium slightly in excess of the chemical equivalents of the sulfateof lime'or sulfates of lime and magnesia present, thus forming sulfateof barium and carbonate of lime and (or) carbonate of magnesia, all ofwhich substances are insoluble in the concentrated brine. The chemicalreactions are as follows:

CaSOi+BaCO3 CLCO3+BESO4 MgSOi+BaCO3= MgCO3+BaSO4.

The sulfate of baryta being insoluble is precipitated and can beremoved, while a pure brine remains behind. A precisely similar solutionwhere operated upon, instead of c1110- rid of sodium.

In order to carry out the purification with such speed as to obtainpractical results, I

, 7 5 process is adopted for a chlorid-of-potassium find it is necessaryto use carbonate of barium cation I do not allow this precipitatedcafbonate of barium to be dried, as by drying I find that its chemicalactivity is seriously diminished; but I use it in the moist condition,in which state it reacts with at least thirty to has not been convertedinto sulfate of barium.'

Provided that the treatment has been properly regulated the amount ofunconverted carbonate of barium is practically m'l. Themixed precipitateobtained as described I remove by settling or filter pressing andafterward treat with sulfuric acid or hydrochloric acid or carbonic acidor sulfurous acid, any of which dissolve out the carbonates of lime andmagnesia, leaving sulfate of barium, which may be reduced with coal inthe usual way and used to produce fresh carbonate of barium from thesulfid by treating with carbonic acid. I find it to be speciallyadvantageous to use sulfurous acid for treating the precipitate asdescribed; butI do not confine myself to any particular acid.

In describing the process in the case of brine it is obvious that othersoluble chlorids of bases the sulfates of which are soluble can also bepurified in the same manner, and the invention may also be used fornitrates of soda and other salts.

I claim as my invention-- 1. The process for treating alkaline chloridsolutions, which consists in adding to the solution a sulfate of thealkali whose chlorid is to be purified in an amount chemicallyequivalent to the chlorids of calcium and magnesium present in thesolution, then adding the chemical equivalent in lime of the deleteriousamount of magnesia present whereby calcium sulfate is formed andmagnesium hydrate is precipitated, then adding freshly-precipitatedbarium carbonate to the mass, the chemical equivalent of the amount ofalkaline earth sulfate present in the solution, and lastly, treating theresulting sulfate of baryta so as to obtain further freshly-precipitatedbarium carbonate for further use.

2. The step in the purification of alkaline chlorid solutions, whichconsists in precipitating the alkaline earth sulfate byfreshlyprecipitated and still-hydrated carbonate of barium.

3. The step in the process of treating alkaline chlorid solutions, whichconsists in changing the chlorids of the alkaline earths present intosulfates by means of the sulfate of the alkali whose chlorid solution isto be treated, and then precipitating the sulfates by means of carbonateof barium.

In witness whereof I have hereunto signed my name, this 15th day ofNovember, 1902, in the presence of two subscribing witnesses.

WILLIAM TRANTOM.

Witnesses:

WM. P. THOMPSON, G. C. DYMOND.

